Trees to provide free energy - no matches required

Everyone knows that trees are a valuable source of energy, but until now harnessing that energy has typically involved cutting them down and burning them.

However, a research group at the Massachusetts Institute of Technology (MIT) reckons that it has worked out a way to draw power from trees without doing them the slightest harm.

The team has developed a technology capable of harnessing the small voltage that results from the difference in PH between the tree and the ground.

In a recent paper, the team attributed the voltage to "a biological concentration cell likely set up by the homeostatic mechanisms of the tree".

The researchers have launched a start up called Voltree that claims to have generated sufficient electricity from the technology to power a wireless network of thousands of tiny humidity and temperature sensor nodes that can be distributed throughout forests to form an early wildfire warning system.

Christopher Love, who helped author the paper, is on the management team of Voltree. Also on the management team are Stella Karavas and Chris Lagadinos of micro engineering firm Magcap LLC, who funded Love's research with $10,000 (£5,800).

Voltree said it is also developing systems for Homeland Security and border protection, remote environmental and agricultural sensors, and climate change research.